Geological characteristics and metallogenic regularity of bauxite in Mianchi,Henan Province
The Mianchi bauxite field is an important bauxite accumulation area in western Henan,where more than 10 large bauxite deposits have been discovered. However,the low degree of comprehensive research on bauxite deposits has resulted in unclear metallogenic regularity and no deep metallogenic prediction has been car-ried out. This paper introduced geological background,orebody,ore minerals and geochemical characteristics of Mianchi bauxite field in detail,focusing on the orebody characteristics,mineral composition,ore structure and main chemical composition of Houling and Lizhuangzhai bauxite deposits. Based on the analysis of the chemical composition changing rule,the weathering intensity of provenance,the weathering depositional environment,the metallogenic materials and the metallogenic regularities in aluminum-bearing rock series,combined with the re-search results of lithofacies paleogeography and tectonic evolution of aluminum-bearing rock series,it is proved that Mianchi bauxite has experienced multi-stage and periodic deposition and is the product of long-term weather-ing residual accumulation. The ore-forming materials of bauxite in Mianchi is multi-source. Leaching during bauxite formation results in significant improvement in ore grade. The bauxite deposit has the characteristics of multi-sedimentary center mineralization controlled by paleo-karst terrain. During the forming of bauxite,the Mi-anchi area was a gently inclined peneplain karst terrain,and bauxite extensively enriched in this area. After multi-stage structural transformation after diagenesis,a tectonic pattern dominated by syncline was formed in Mianchi,which deeply buried the ore-bearing strata in the core and south wing of the syncline,and it is predicted that large-scale high-quality bauxite still exists in the middle and deep parts of the syncline.
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